Orientador: Elias Basile Tambourgi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-11T04:08:18Z (GMT). No. of bitstreams: 1 Freitas_JeffersonArlen_D.pdf: 3985383 bytes, checksum: 8a45be364ed2c151ea51fbb373ede3d6 (MD5) Previous issue date: 2007 / Resumo: Este trabalho tratou da pesquisa e desenvolvimento de um adsorvente alternativo, aplicável no tratamento de rejeitos líquidos industriais, contendo baixas concentrações dos metais pesados Cd, Cu e Zn. Ele teve como objetivo geral produzir esferas adsorventes de zeólita 4A - Sargassum sp. com custo de produção competitivo e com elevada capacidade de captura dos metais pesados Cd, Cu e Zn, nas quais o processo de adsorção ocorra com elevada eficiência e com cinética favorável. A produção das esferas envolveu uma abordagem inovadora do Processo Sol - Gel, a qual permitiu produzir sete tipos de esferas, partindo da combinação e imobilização de adsorventes tradicionais pesquisados: biomassa Sargassum sp., caulim, alumina e zeólita. Este processo de imobilização das partículas dos adsorventes tradicionais causa uma obstrução dos poros e canais existentes nestas partículas e, com isto, reduz a capacidade de captura dos metais pesados nas esferas resultantes. Felizmente, a combinação de adsorventes realizada viabilizou a obtenção de esferas adsorventes com elevada capacidade de captura de metais pesados e com cinética favorável. É o caso das esferas de zeólita 4A, com capacidade máxima de captura de Cd+Cu+Zn de 746 µmol/g, com uma velocidade de captura aproximada de 18 µmol/g.h e com uma eficiência de captura de 82% e das esferas de zeólita 4A - 50% em peso de Sargassum sp., com capacidade máxima de captura de Cd+Cu+Zn de 709 µmol/g, com uma velocidade de captura aproximada de 20 µmol/g.h e com uma eficiência de captura de 83%. O comportamento de adsorção destas esferas se ajustou ao modelo de equilíbrio de Freundlich. Elas possuem uma cinética de adsorção compatível com o modelo cinético de pseudo-segunda ordem. Ao tratarem um efluente industrial real, estas esferas apresentam uma eficiência de captura de Cd+Cu+Zn =90% enquanto que numa resina quelante comercial esta eficiência é de 99,5%. Tem-se, pois, esferas adsorventes com elevada eficiência e baixo custo de produção, tornando-as um bom adsorvente para aplicação no tratamento de efluentes líquidos industriais com baixa concentração de Cd, Cu e Zn / Abstract: In this work had been made a research and the development of an alternative adsorbent which may be applied in the treatment of industrial liquid effluents containing low concentration of heavy metals, Cd, Cu and Zn. The main objective was to produce 4A type zeolite-Sargassum sp. adsorbents spheres with the following characteristics: competitive fabrication cost; high uptake capacity of the heavy metals, Cd, Cu and Zn; high affinity by the referred heavy metals; and appropriated adsorption kinetic. The marking of the adsorbents spheres had involve the innovative use of the Sol-gel Process. That had permitted to obtain seven types of adsorbents spheres for combination and immobilization of the particles of traditional adsorbents Sargassum sp., kaolin, alumina and 4A type zeolite. This immobilization process causes an obstruction of the pores and the channels present in these particles that reduced the uptake capacity of the produced adsorbents spheres. Fortunately, the combination of traditional adsorbents particles produced adsorbent spheres with high uptake capacity, high uptake efficiency, and appropriate adsorption kinetic. As, two types of adsorbent spheres, 4A type zeolite and 4A type zeolite-50% Sargassum sp. adsorbed 746 µmol/g and 709 µmol/g with an adsorption velocity of 18 µmol/g.h and 20 µmol/g.h, and a uptake efficiency of 82% and 83%, respectively. The adsorption behavior of these adsorbent spheres had been fitting to the Freundlich model. They have an adsorption kinetic compatible with the pseudo-second order model. When it treated an industrial liquid effluent with these adsorbent spheres, they showed a uptake efficiency higher than 90% and while an uptake efficiency of 99,5% is shown for the commercial chelant resin / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

O tratamento de efluentes de indústrias e efluentes domésticos é realizado em Estações de Tratamento de Esgoto as chamadas (ETE\'s), onde se tem como produtos finais, uma corrente de água tratada e um resíduo sólido, o lodo de esgoto. A presente Tese tem como objetivo o estudo do processamento térmico do lodo de esgoto seco da ETE de Barueri, São Paulo, visando avaliar seu uso como fonte de energia e obter, por queima, um material cerâmico. Este trabalho foi proposto como uma alternativa para o reuso deste material, eliminando sua disposição final no solo. Evita-se, assim, a contaminação pelos materiais contidos nas cinzas obtidas nesse processo e, conseqüentemente, a contaminação de lençóis de água subterrâneos. Foi feita a caracterização do lodo e dos principais produtos obtidos nas diversas etapas de queima do lodo, que foram estudadas principalmente por análises térmicas, complementadas por outras análises instrumentais. Os resultados indicam a possibilidade de utilizar o lodo como fonte alternativa de energia, visto ter apresentado um poder calorífico inferior da ordem de 40% do de um óleo combustível. O tratamento térmico em presença de ar, aplicado ao lodo de esgoto até a temperatura de 1050°C, elimina totalmente os componentes orgânicos presentes no lodo original. O material cerâmico final, formado do processamento térmico dos argilo-minerais originalmente presentes no lodo, apresenta os elementos traço de metais pesados fixados na matriz cerâmica sinterizada assim obtida. Ensaios de lixiviação ácida e de solubilidade em água indicam a possibilidade de uso deste material sólido final em formulações cerâmicas, sem prejuízo à saúde humana e ao meio ambiente. / The domestic and industrial wastewater goes to a treatment station. The effluent is a water with na low level of pollution. The solid waste generated is the dry sludge. This is the object of the present Dissertation. We intend to use the sludge as a source of energy and also as a raw material for the ceramic industry. The heating power of the dry sludge is close to 40% of the value reported for heating oil. Using the ashes as ceramic raw material there will no contamination of the underground water. Characterization of the sludge fired at 1050°C were performed through thermal analysis, x-ray diffraction, x-ray fluorescence and scanning electron microscopy. The leaching test of the calcinated sludge shows very low concentration of contaminants. Therefore the technique is applicable for the recycle of wastewater sludge.

The goal of this thesis is to generate fundamental understandings of charge transport behaviors of composites consisting of garnet structured Al substituted Li7La3Zr2O12 (LLZO) electrolyte and LiCoO2 electrode. In order to take full advantage of all-solid-state batteries, bulk type composite electrodes should be introduced to increase energy and power density. However, the charge utilization of bulk type composite electrodes is quite low. Understanding ionic conduction behavior is, therefore, important for improving the performance of all-solid-state batteries, because ion conduction within solids depends on effective pathways. Electronic conductivity can be easily compensated by adding carbon black, but ionic conductivity can only depend on composites electrode itself. Here, we show that electronic and ionic conductivities of composites consisting of LiCoO2 and Al doped LLZO can be achieved separately. 3D reconstructed image obtained from focused ion beam-scanning electron microscope (FIB-SEM) demonstrates that porosity, percolation, and grain boundaries often play antagonistic roles in controlling the charge transport behaviors in the composite electrodes, resulting in an overall conductivity dominated by electrons. This work suggests an approach to optimize electronic and ionic conductivities for bulk type composite electrodes, which may eventually be utilized in all-solid-state batteries.

Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12335号 / 論工博第4013号 / 新制||工||1466(附属図書館) / 27190 / UT51-2009-D550 / (主査)教授 森山 裕丈, 教授 伊藤 秋男, 教授 高木 郁二 / 学位規則第4条第2項該当

Tantalum carbide (TaC) and hafnium carbide (HfC) possess extremely high melting points, around 3900 oC, which are the highest among the known materials. TaC and HfC exhibit superior oxidation resistance under oxygen deficient and rich environments, respectively. A versatile material can be expected by forming solid solutions of TaC and HfC. However, the synthesis of fully dense solid solution carbide is a challenge due to their intrinsic covalent bonding which makes sintering challenging. The aim of the present work is to synthesize full dense TaC-HfC solid solutions by spark plasma sintering with five compositions: pure HfC, HfC-20 vol.% TaC (T20H80), HfC- 50 vol.% TaC (T50H50), HfC- 80 vol.% TaC (T80H20), and pure TaC. To evaluate the oxidation behavior of the solid solutions carbides in an environment that simulates the various applications, an oxygen rich, plasma assisted flow experiment was developed. While exposed to the plasma flow, samples were exposed to a temperature of approximately 2800 oC with a gas flow speed greater than 300 m/s. Density measurements confirm near full density was achieved for all compositions, with the highest density measured in the HfC-contained samples, all consolidated without sintering aids. Confirmation of solid solution was completed using x-ray diffraction, which had an excellent match with the theoretical values computed using Vegard’s Law, which confirmed the formation of the solid solutions. The solid solution samples showed much improved oxidation resistance compared to the pure carbide samples, and the T50H50 samples exhibited the best oxidation resistance of all samples. The thickness of the oxide scales in T50H50 was reduced more than 90% compared to the pure TaC samples, and more than 85% compared to the pure HfC samples after 5 min oxidation tests. A new Ta2Hf6O17 phase was found to be responsible for the improved oxidation performance. Additionally, the structure of HfO2 scaffold filled with molten Ta2O5 was also beneficial to the oxidation resistance by limiting the availability of oxygen.

Diploma thesis is focused on machining of refractory ceramics materials. The theoretical part describes the division of ceramics materials, their structure, manufacture and properties. This part also contains the division of refractory ceramics. In the second chapter, of ceramics materials are described machining. The latest chapter is focused on analyzing the machinability of ceramics materials R - SLI - K. During the experiment, cutting conditions were changed and cutting forces were checked. Then surface roughness was measured and tool wear was observed.

Diploma thesis contains introduction of a company P-D Refractories CZ a. s., where the manufacture of ceramic chimney liners is. Followed by a description and analysis of the product in the entire production cycle, material and product spectrum. Based on the results of current production is created proposal to streamline the machining technology with a view to increase productivity and reduce defective products, which means determine the material of a tool and the method of machining. The work is finished by technical-economic assessment, where the summary and recommendation of the proposed solution are.

Proton conducting intermediate temperature (600oC-400oC) solid oxide fuel cells (IT-SOFC) have many potential advantages for clean and efficient power generation from readily available hydrocarbon fuels. However, it still has many unsolved problems, especially on the anode where the fuel got oxidized and the cathode where oxygen got reduced. In this study, for the anode, the effects of hydrogen sulfite (H2S) and carbon dioxide (CO2) as fuel contaminants were studied on the nickel (Ni) based cermet anode of proton conducting IT-SOFC using proton conducting electrolyte of BaZr0.1Ce0.7Y0.1Yb0.1O3 (BZCYYb). Both low-ppm level H2S and low-percentage level CO2 caused similar poisoning effects on the anode reaction. The H2S poisoning effect was also found to be much less than on oxide-ion conducting SOFC, which is attributed to the absence of water evolution for the anode reaction in proton conducting SOFC. In addition, the H2S/CO2 poisoning mechanisms were investigated using X-ray diffraction, energy dispersive spectroscopy (EDS), Raman spectroscopy, and secondary ion mass spectroscopy (SIMS). For H2S, other than possible sulfur dissolution into BZCYYb, no bulk reaction was found, suggesting sulfur adsorption contributes to the reduced performance. For CO2, reaction with BZCYYb to form BaCO3 and CeO2 is identified and is believed to be the reason for the sudden worsening in CO2 poisoning as temperature drops below ~550oC. For the cathode, several representative SOFC cathodes including silver (Ag), La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), LSCF-BZCYYb composite, and Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) were evaluated based on BZCYYb electrolyte. LSCF give similar high interfacial resistance as Ag, while LSCF-BZCYYb composite cathode shows lower interfacial resistance, suggesting LSCF behaves like pure electronic conductor cathode in this case. For BSCF, it shows smallest interfacial resistance and the charge transfer process appears to accelerate with the introduction of H2O, while oxygen adsorption/transport seem to slow down due to adsorbed H2O. Furthermore, CO2 was shown to cause poisoning on the BSCF cathode, yet the poisoning was significantly reduced with the co-presence of water. The results suggest that although BSCF seem to display mixed proton-electronic conduction, its strong affinity to H2O may inhibit the oxygen reduction reaction on the cathode and new cathode materials still need to be designed.

The doctoral thesis is orientated to preparation of advanced ceramic materials by electrophoretic deposition (EPD). The vertical mode of EPD in constant current regime was used in this study. The morphology of prepared materials (image structural analysis), physical properties (EPD yields, relative density, roughness of deposit surface) and mechanical properties (hardness, fracture toughness, elastic module) were characterized on the prepared deposits from alumina (Al2O3), zirconia (ZrO2) or their composites. It was found that the surface charge of alumina or zirconia particles was opposite (inversion charge) in stabilized isopropanolic dispersions than in case of water dispersions. The model of alumina or zirconia particles “inverse” stabilization was proposed. This type of EPD was further studied in presence of different acidic stabilizers. The obtained results from the experimental work (-potential and electric conductivity of dispersions, EPD yields, relative density of deposits, roughness of deposit surface etc.) showed the monochloracetic acid as the optimal type of acidic stabilizer. The kinetic of EPD process from dispersions containing isopropanol, monochloracetic acid and Al2O3 or ZrO2 particles and its influence on the final properties of prepared deposits was studied. The new method of kinetic measurement was developed. Due to good knowledge of EPD kinetic the ceramic laminates (Al2O3/ZrO2) with optimized layer thickness were prepared. The internal stresses and their influence on crack trajectory in ceramic laminates contained 100-150 strongly bonded layers were studied. It was found that the dominant role of crack deflection played the internal compressive stresses, i.e. with increasing of amount of internal compressive stresses the crack deflection was also increased. This work brought a new knowledge in the area of non-aqueous ceramic dispersion stabilization and preparation of heterostructured ceramic materials.

No description available.